German Patent Disclosure Document DE-OS 35 36 820 Bragas and Busch/BOS a traffic broadcast decoder that is arranged to process digital signals. These digital signals are for instance superimposed on an auxiliary carrier that is broadcast by radio stations, or transmitters, together with the FM radio program. As a result, the information present in these digital signals can be transmitted unimpeded, parallel with the actual radio program. This applies particularly to traffic news, which can be decoded by demodulation of the aforementioned auxiliary carrier. Besides signal transmission by means of auxiliary carriers, however, it is also possible for these digital signals to be supplied to a digital radio transmitter, for instance interlaced with the digital radio information.
If the traffic news transmitted as digital signals is formatted on the same principle as traffic news broadcast in the clear, then instead of the complete information, it is also possible to transmit memory addresses, which invoke standardized texts stored in memories in the receivers. This makes a substantially smaller data capacity adequate for transmission. As a consequence, substantially more traffic news on individual events can be provided than was the case previously.
While keeping the same selection criteria as before for the traffic news, which depends essentially on the number of drivers affected, traffic news relating to a larger, supraregional geographical area, e.g. the region of the Federal Republic of Germany and possibly the neighboring countries, could also be transmitted over all the chains of FM stations. Another possibility is to restrict the region into which the traffic news relates to approximately the region supplied by the station or chain of stations, but in return to expand the selection of traffic news to events that affect even only a few drivers.
Whatever selection is made for the traffic news transmitted, the great number of reports would be excessively demanding of the driver's attention if he received them all in a visual or acoustic form.
It has already been proposed that a selection from among the traffic news be made to decide what will be displayed or reproduced. This can be done for instance in terms of the intended trip route, which the driver has input via an input device in the form of data on the section of highway to be traveled. It is then assured that only the traffic news that applies to that trip route will appear on the output device.
Still, making a limitation to the trip route selected may be too narrow, if the driver should become interested in the traffic situation elsewhere or in relatively persistent bottlenecks in other places, because he might wish to drive to those places soon.
In German Patent Application P 39 14 104.7 and corresponding PCT/DE 90/00250, the publishing dates which do not precede the international filing date of the present application, it has already been proposed that a selector be provided in the radio receiver, by means of which the radio receiver user can individually specify a region for which he wishes to have information on the traffic situation. Based on this specification, a station is then sought that essentially transmits information on this region. It is also possible as a result to incorporate filters that filter out traffic news beyond the local region that is for instance also broadcast by the same station, so that only the information that actually refers to the selected region is output.
Manually inputting a certain region makes input means such as keyboards a prerequisite, and it is also somewhat inconvenient for the user, because if he wishes to obtain the regional traffic news he has to input the applicable region first. Often, therefore, he does not bother, and so the danger still exists that the radio user will either be overwhelmed by unnecessary information or, having tuned to a station from a different region, will either not receive the desired traffic news, or will not receive all of it.